Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding Used to Compute Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Accounting Policies [Abstract]
Net income	$ 5,090	$ 7,815	$ 13,020	$ 15,287
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)	11,665	11,513	11,638	11,475
Dilutive potential common shares (in shares)	163	245	207	279
Diluted weighted-average common shares outstanding (in shares)	11,828	11,758	11,845	11,754
Earnings per share
Basic (in dollars per share)	$ 0.44	$ 0.68	$ 1.12	$ 1.33
Diluted (in dollars per share)	$ 0.43	$ 0.66	$ 1.10	$ 1.30